A study on the elastic coefficients of setback micro-springs for a MEMS safety and arming device

This paper analyzed the effects of setback micro-springs on a MEMS safety and arming (S&A) device. To make up for defects related to current methods of obtaining the elastic coefficients of micro-springs, a computational formula for the elastic coefficients of S-shaped micro-springs was developed in accordance with Castigliano’s second theorem and Hooke’s law and verified for three types of setback micro-springs with different structures through finite element simulations and a self-designed testing system for the elastic coefficients of micro-springs. The testing values and the simulation values were in good agreement with the theoretical values. The results indicate that the precise measurement and calculation of the elastic coefficients of micro-springs in the transverse, longitudinal and vertical directions can be realized with the method presented in this paper. For the S-shaped setback micro-spring, the elastic coefficient in the transverse direction is the smallest and the most prone to fracture and plastic deformation. In the design of MEMS S&A devices, priority should be given to applying the deformation of the micro-spring in the longitudinal and vertical directions.